DESCRIPTION: Chronic Fatigue Syndrome (CFS) and chronic fatigue (CF) are severe, disabling conditions. Few studies have examined the natural history course of CFS and chronic fatigue over time, particularly in random, community-based, multi-ethnic populations. In the past, almost all studies with samples of CFS and chronic fatigue patients have relied on referrals from physicians or health facilities, which biased the sample by illness, help-seeking behaviors, or differential access to health are. In contrast, a recent community-based study found the prevalence rate of CFS to be 4% among adults, and the prevalence of CFS among adults was higher among Latino and African-American samples than among the White sample (Jason et al., 1999). These findings might be due to the fact that this sample was collected from an urban area, and a community-based approach was used, thus minimizing the influence of biased data collection procedures. The proposed study will rigorously evaluate the natural history of CFS and chronic fatigue in an ethnically and socioeconomically diverse sample unbiased by illness and help-seeking behaviors, or by differential access to the health care system. Increasingly, the studies suggest that a variety of socio-environmental and psychological risk factors are associated CFS and chronic fatigue maintenance over time. We will perform follow-up on Wave 1 subjects with CFS and chronic fatigue to determine if the associations identified in Wave 1 between CFS and a variety of risk factors will be associated with poorer prognosis in Wave 2. Similar comparisons will be conducted for those with chronic fatigue. Major benefits of this grant application are the diversity of the population, identification of cases from the community rather than the health care system, and the use of a medical exam to confirm CFS and chronic fatigue diagnoses.